Merging some elements inside a list

Question

Given this nested list:

nested_lst = [u'Tom', ['50', ' 1.85', ' 112', ' 60', ' 1.90', ' 115']]

I'd like to join every 3 elements of nested_lst[1] for the result of:

nested_lst = [u'Tom', [('50', ' 1.85', ' 112'), (' 60', ' 1.90', ' 115')]]

Sorry, book recommendations are off-topic for Stack Overflow, they simply do not fit the format here. — Martijn Pieters, May 03 '13 at 11:23
@MartijnPieters: Ok, clear ... I will remove my answer for clearity. — Michel Keijzers, May 03 '13 at 11:27

Ashwini Chaudhary · Accepted Answer · 2013-05-03T11:29:06.707

Use a list comprehension:

>>> nested_lst = [u'Tom', ['50', ' 1.85', ' 112', ' 60', ' 1.90', ' 115']]
>>> x=nested_lst[1]

>>> nested_lst[1]=[ tuple(x[i:i+3]) for i in xrange(0,len(x),3) ]
>>> nested_lst
[u'Tom', [('50', ' 1.85', ' 112'), (' 60', ' 1.90', ' 115')]]

or you can also use itertools.islice:

>>> from itertools import islice
>>> nested_lst = [u'Tom', ['50', ' 1.85', ' 112', ' 60', ' 1.90', ' 115']]
>>> x=nested_lst[1]
>>> it=iter(x)

>>> nested_lst[1]=[tuple( islice(it,3) ) for i in xrange(len(x)/3)]
>>> nested_lst
[u'Tom', [('50', ' 1.85', ' 112'), (' 60', ' 1.90', ' 115')]]

score 2 · Answer 2 · edited May 23 '17 at 11:43

2

Typically you'd use a list comprehension like @AshwiniChaudhary has posted, but here's an alternate solution using this technique

>>> nested_lst = [u'Tom', ['50', ' 1.85', ' 112', ' 60', ' 1.90', ' 115']]
>>> [nested_lst[0], zip(*[iter(nested_lst[1])]*3)]
[u'Tom', [('50', ' 1.85', ' 112'), (' 60', ' 1.90', ' 115')]]

edited May 23 '17 at 11:43

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answered May 03 '13 at 11:24

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Merging some elements inside a list

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